In order to meet the requirements of load power and reliability, the power system often adopts the distributed system to use several power supply modules in parallel. In the process of using in parallel, because the diversity of the power supply modules, the current shared on each module will be different, and then it is caused that the current stresses and the thermal stresses on each module are different, thus the reliability of the system is reduced. In order to ensure the current-sharing of the current among multiple power supplies in the system and the uniform distribution of the current stress and the thermal stress, the power supply module must support the parallel current-sharing function.
At present, the power system requires that power supplies realizing different power levels can be mixed plugging and used in parallel; although there are a lot of schemes of the automatic current-sharing in the related art, most are the current-sharing according to 1:1, which will must cause that the load of the low power module is overweight (as to the low power module itself), and the load of the high power module is too light (as to the high power module itself). Those skilled in the art should know that, as to the power supply module, no matter the load is overweight or the load is too light, neither the working condition of the power supply module is the optimum state, including but not limited to that the working efficiently does not reach the highest, the current and the voltage and the thermal stress are not under the optimum working condition and even under the situation of the abominable working condition, which will influence the life time of the power supply module and the global reliability of the power system.
If there are two modules A (1000 W) And B (2000 W) of different power levels which are mixed plugging for current-sharing, and the system load is 2000 W, and module A and module B will all be loaded 1000 W if according to 1:1 current-sharing, then module A is fully loaded, and module B is only loaded 50%. At this moment, both the two modules are not working on the optimum working point, and the efficiencies do not reach the highest; module A works at the maximum output power, and the current stress and the thermal stress of the module A are in the most abominable working condition, so the life time of the module and the reliability of the whole power system will be influenced.